Editing Equation of state (section)

=== Classical ideal gas law ===
The classical [[ideal gas law]] may be written
<math display="block">pV = nRT.</math>

In the form shown above, the equation of state is thus
<math display="block">f(p, V, T) = pV - nRT = 0.</math>

If the [[Perfect gas|calorically perfect]] gas approximation is used, then the ideal gas law may also be expressed as follows
<math display="block">p = \rho(\gamma - 1)e</math>
where <math>\rho</math> is the [[number density]] of the gas (number of atoms/molecules per unit volume), <math>\gamma = C_p/C_v</math> is the (constant) adiabatic index ([[heat capacity ratio|ratio of specific heats]]), <math>e = C_v T</math> is the internal energy per unit mass (the "specific internal energy"), <math>C_v</math> is the specific heat capacity at constant volume, and <math>C_p</math> is the specific heat capacity at constant pressure.